CN105140940A - Method for determining capacity of energy storage device integrated with independent new energy system - Google Patents

Abstract

The invention discloses a method for determining capacity of an energy storage device integrated with an independent new energy system. The method can be applied to scientific research and engineering application in related fields of new energy. An optimal allocation method for stored energy of the independent new energy system is provided on the basis of the discrete fourier transform theory and the signal energy concept according to wind light power data; and optimal allocation can be carried out on the stored energy of independent wind storage system and light storage system; and the energy storage capacity can be rapidly and accurately configured according to the user requirements, so that the requirements of an energy storage design in practical engineering can be met.

Description

A kind of method determining independent new energy resources system access capacity of energy storing device

Technical field

The present invention relates to a kind of method determining independent new energy resources system access capacity of energy storing device, belong to technical field of new energy power generation.

Background technology

Occupy certain proportion in the supply of electric power at home and abroad of the large-scale application of current generation of electricity by new energy, active and effective effect has been served to energy-saving and emission-reduction, development clean energy resource.In the utilization of generation of electricity by new energy, because wind-powered electricity generation wherein, photovoltaic generation etc. are by the impact of meteorologic factor, there is intermittence, stochastic volatility, cause output-power fluctuation, bring very important negative effect to electrical network and load.Chinese scholars stabilizes by designing the mode of energy storage device the power fluctuation that renewable energy power generation produces by meteorological factor influence.

Energy storage technology realizes energy balance, ensures the important means that electrical network normally runs to have the effect of irreplaceable support and optimization.But because the capacity of energy storage configuration configures according to maximization, and cost of investment is high, does not have economy.So from the viewpoint of the economy of cost of investment and the validity of functional realiey, during stored energy application, rational capacity configuration is necessary.In Practical Project, the choosing of stored energy capacitance normally realizes by rule of thumb, thus is difficult to the accuracy ensureing stored energy capacitance size.Therefore, need to rely on local sights characteristic, rely on algorithm quick and precisely to determine stored energy capacitance, effectively improve the output characteristic of honourable power.

Summary of the invention

Goal of the invention: the present invention is directed to the needs that domestic generation of electricity by new energy technology improves, proposes a kind of method determining independent new energy resources system access capacity of energy storing device, can be applicable to technical field of new energy power generation.

Technical scheme: the present invention for achieving the above object, adopts following technical scheme: a kind of method determining independent new energy resources system access capacity of energy storing device, comprises the following steps:

1) discrete Fourier transform is carried out to the power data obtained, obtain amplitude frequency curve;

2) spectrum analysis is carried out to power data, eliminate DC component, carry out inverse discrete Fourier transform and change, obtain the power data eliminating DC component, i.e. reference data;

3) characteristic frequency and specific power data is supposed;

4) introduce the concept of signal energy, calculate the ratio of energy and reference energy;

5) stored energy capacitance is obtained by setup time and energy storage power calculation.

As optimization, in step 1) in, the amplitude-frequency result formula after Fourier transform:

$\left\{\begin{array}{c}S=F\left(P\right)={\[}^S\\ f={\[f\[1\],...,f\[i\],...,f\[N\]\]}^T\end{array}\right.;$

In formula: N is the number of sampled point; P is power data, P=[P [1] ..., P [i] ..., P [N]] ^t; F (P) is for carry out Fourier transform to power data; S [i] is the amplitude of i-th f [i], and S [i]=R [i]+jI [i], R [i] and I [i] is respectively real part and imaginary part; F is sample frequency, f [i]=f (i-1)/N.

As optimization, in step 2) in, the formula eliminating DC component is:

$S_0\[i\]=\left\{\begin{array}{cc}0+j0& f_i=0\\ S\[i\]& f_i\≠0\end{array}\right.;$

Eliminate power data (reference data) P of DC component ₀formula is:

P ₀＝F ^-1(S ₀)＝[P ₀[1],...,P ₀[i],....,P ₀[N]] ^T；

In formula, F ^-1(S ₀) be to S ₀carry out discrete Fourier transform; P ₀[i] is the power data (reference data) of elimination DC component, in the data of i-th sampled point.

As optimization, in step 3) in, suppose a characteristic frequency f (T=1/f), then one group of specific power data P ₁formula is:

$S_1\&lsqb;i\&rsqb;=\left\{\begin{array}{cc}0+j0& f_i<0\\ S_0\&lsqb;i\&rsqb;& f_i\&GreaterEqual;0\end{array}\right.;$

P ₁＝F ^-1(S ₁)＝[P ₁[1],...,P ₁[i],....,P ₁[N]] ^T；

In formula, F ^-1(S ₀) be to S ₁carry out discrete Fourier transform; P ₁[i] is specific power data, in the data of i-th sampled point; Specific power data P ₁periodic region between be 0-T.

As optimization, in step 4) in, signal energy is defined as follows:

$E=\sqrt{\underset{i=1}{\overset{N}{\&Sigma;}}x{\&lsqb;i\&rsqb;}^2};$

In formula, E is the energy of signal; X [i] is the power data of i-th sampled point;

ENERGY E ₁with reference energy E ₀the computing formula of ratio is as follows:

η＝E ₁/E ₀。

As optimization, in step 5) in, the mean value of original power data is set as energy storage power, obtains stored energy capacitance by setup time and energy storage power.

Technique effect: the present invention compared with prior art: the method adopting determination independence new energy resources system proposed by the invention access capacity of energy storing device, capacity of energy storing device can be established rapidly and accurately, effectively improve new energy electric field power out-put characteristic, play the effect of generation of electricity by new energy in electric power system better, to the economy of new energy electric field be all of great importance to its meritorious regulating power.

Accompanying drawing explanation

Fig. 1 is the data of wind power generation power whole year in somewhere;

Fig. 2 is the data in wind power generation power January in somewhere;

Fig. 3 is the amplitude-versus-frequency curve of somewhere wind power generation power data;

Fig. 4 is the wind power generation power data (reference data) eliminating DC component;

Fig. 5 is the idiographic flow determining setup time.

Specific embodiments

Be described in detail below in conjunction with the techniqueflow of accompanying drawing to invention:

The principle of the invention for convenience of explanation, the present invention have chosen the wind power data in somewhere as research object.Fig. 1 and Fig. 2 respectively illustrates the whole year in somewhere and the wind power data in January.From Fig. 1 and Fig. 2, the annual mean of wind power is 9.5976kW, and the maximum of power reaches 335kW; The fluctuation of wind power is quite large.This phenomenon is caused by the weather conditions in somewhere and wind characteristic.

1) discrete Fourier transform (DFT) is carried out to the power data obtained, thus obtain amplitude frequency curve.The amplitude-frequency result after DFT (frequency domain) is given in following formula:

$\left\{\begin{array}{c}S=F\left(P\right)={\&lsqb;}^S\\ f={\&lsqb;f\&lsqb;1\&rsqb;,...,f\&lsqb;i\&rsqb;,...,f\&lsqb;N\&rsqb;\&rsqb;}^T\end{array}\right.;---\left(1\right)$

In formula: N---the number of sampled point;

P---power data, P=[P [1] ..., P [i] ..., P [N]] ^t;

F (P)---DFT is carried out to power data;

S [i]---the amplitude of i-th f [i], S [i]=R [i]+jI [i], R [i] and I [i] is respectively real part and imaginary part;

F---sample frequency, f [i]=f (i-1)/N.；

Carry out spectrum analysis to the wind power generation power data (whole year) in the somewhere in Fig. 1, obtain corresponding amplitude-frequency characteristic, as shown in Figure 3, time its f=0 (DC component), its amplitude is 9.5976 to concrete curve.For being greater than 2 × 10 in wind power ^-4the amplitude of Hz frequency is close to 0.

2) spectrum analysis is carried out to power data, eliminate DC component, carry out inverse discrete Fourier transform and change (IDFT), obtain the power data (reference data) eliminating DC component.After spectrum analysis is carried out to power data, wherein DC component (frequency is 0) be wind power generation with energy-storage system combine output, be that the ideal of whole system exports target.When determining setup time, do not need to consider immediate component, therefore, in second step, first eliminate DC component.Specifically can be calculated by formula (2):

$S_0\&lsqb;i\&rsqb;=\left\{\begin{array}{cc}0+j0& f_i=0\\ S\&lsqb;i\&rsqb;& f_i\&NotEqual;0\end{array}\right.;---\left(2\right)$

To S ₀carry out inverse discrete Fourier transform to change (IDFT), then can obtain power data (reference data) P eliminating DC component ₀.Here P ₀for reference data, it is one of important parameter in energy storage layoutprocedure.

P ₀＝F ^-1(S ₀)＝[P ₀[1],...,P ₀[i],....,P ₀[N]] ^T；(3)

Wherein, F ^-1(S ₀)---to S ₀carry out IDFT;

P ₀[i]---eliminate the power data (reference data) of DC component, in the data of i-th sampled point.

Eliminate the wind power generation power data curve of DC component, moved down 9.5976kW by Fig. 1 and Fig. 2 entirety, the datum line of the longitudinal axis has become-9.5976kW, and Fig. 4 is the reference data calculating wind power generation power energy ratio.

3) characteristic frequency and specific power data is supposed.Based on S in second step ₀with, P ₀, suppose a characteristic frequency f (T=1/f), then one group of specific power data P ₁can be calculated by formula (4) and formula (5).

$S_1\&lsqb;i\&rsqb;=\left\{\begin{array}{cc}0+j0& f_i<0\\ S_0\&lsqb;i\&rsqb;& f_i\&GreaterEqual;0\end{array}\right.;---\left(4\right)$

P ₁＝F ^-1(S ₁)＝[P ₁[1],...,P ₁[i],....,P ₁[N]] ^T；(5)

In formula, F ^-1(S ₀)---to S ₁carry out IDFT;

P ₁[i]---specific power data, in the data of i-th sampled point; Specific power data P ₁periodic region between be 0-T.

4) introduce the concept of signal energy, calculate the ratio of energy and reference energy.Introduce the concept of signal energy in the present invention, it is defined as follows:

$E=\sqrt{\underset{i=1}{\overset{N}{\&Sigma;}}x{\&lsqb;i\&rsqb;}^2}---\left(6\right)$

In formula, the energy of E---signal, in the present invention, signal is power data (comprising the power data (reference data) and specific power data of eliminating DC component);

X [i]---the power data of i-th sampled point.

Power data P ₀, P ₁energy be respectively E ₀, E ₁, can calculate by through type (6).In addition, power data (reference data) P of DC component is eliminated ₀e ₀for reference energy.

ENERGY E ₁with reference energy E ₀the computing formula of ratio is as follows:

η＝E ₁/E ₀；(7)

Idiographic flow is as follows:

A) energy Ratios η is set ₀;

B) based on the S in second step ₀all frequency values, characteristic frequency is from low frequency (f _min) to high frequency (f _max) value gradually, utilize formula (4) and (5) to generate new certain power data P ₁;

C) through type (6) and formula (7), calculate ENERGY E ₁with the energy Ratios η of reference energy;

D) when energy Ratios η reaches set point, program then stops, and returns characteristic frequency (finally) value f, and the cycle T of its correspondence, be setup time.In a program, as η-η ₀during <=0.005, then think that energy Ratios η reaches set point; η-η ₀<=0.005, is in program the criterion circulating and terminate.

Idiographic flow as shown in Figure 5.

Determine in the process of setup time, energy Ratios η ₀size directly affects setup time, affected indirectly the configuration capacity of energy storage and the economy of independent wind storage system, therefore set great energy Ratios η ₀seem quite important.For independent new energy resources system, the ratio of important load and energy storage should be fully taken into account in the location of autonomous system, the energy Ratios η that setting is applicable to ₀, obtain practical setup time.

Energy Ratios η is supposed in the present invention ₀=90%, configuring condition setup time of research wind power generation power.

5) mean value of original power data is set as energy storage power P, then stored energy capacitance is obtained by setup time and energy storage power, i.e. P*T.

The mean value of somewhere wind power generation power is 9.5976kW, then the energy storage power configuring wind storage system is 9.5976kW.

According to different energy Ratios η ₀, table 1 gives the corresponding energy storage configuring condition of somewhere independence wind storage system.In table 1, when ensureing 90% of wind power generation power (reference data) energy, setup time is 63.0216h, and the time is long, and economy is lower; And when ensureing 80%, 70%, 60% of reference energy, setup time is down to 30.9541h, 20.0458h, 13.2929h respectively, in these three kinds of situations, both improve the power supply reliability of important load during fault, also ensure that the economy of whole system simultaneously.To sum up, for independent wind storage system, can comprehensively the economy of wind storage system and reliability configure; During in order to ensure higher reliability, energy storage allocating power is 9.5976kW, and capacity is 297.0851kWh; During in order to weigh economy, energy storage allocating power is 9.5976kW, and capacity is 127.5799kWh.

The energy storage configuring condition (different-energy ratio) of table 1 somewhere wind power generation power

Claims (6)

1. determine a method for independent new energy resources system access capacity of energy storing device, it is characterized in that: comprise the following steps:

1) discrete Fourier transform is carried out to the power data obtained, obtain amplitude frequency curve;

2) spectrum analysis is carried out to power data, eliminate DC component, carry out inverse discrete Fourier transform and change, obtain the power data eliminating DC component, i.e. reference data;

3) characteristic frequency and specific power data is supposed;

4) introduce the concept of signal energy, calculate the ratio of energy and reference energy;

5) stored energy capacitance is obtained by setup time and energy storage power calculation.

2. the method determining independent new energy resources system access capacity of energy storing device according to claim 1, is characterized in that: in step 1) in, the amplitude-frequency result formula after Fourier transform:

$\left\{\begin{array}{c}S=F\left(P\right)={\&lsqb;}^S\\ f={\&lsqb;f\&lsqb;1\&rsqb;,...,f\&lsqb;i\&rsqb;,...,f\&lsqb;N\&rsqb;\&rsqb;}^T\end{array}\right.;$

In formula: N is the number of sampled point; P is power data, P=[P [1] ..., P [i] ..., P [N]] ^t; F (P) is for carry out Fourier transform to power data; S [i] is the amplitude of i-th f [i], and S [i]=R [i]+jI [i], R [i] and I [i] is respectively real part and imaginary part; F is sample frequency, f [i]=f (i-1)/N.

3. the method determining independent new energy resources system access capacity of energy storing device according to claim 1, is characterized in that: in step 2) in, the formula eliminating DC component is:

$S_0\&lsqb;i\&rsqb;=\left\{\begin{array}{cc}0+j0& f_i=0\\ S\&lsqb;i\&rsqb;& f_i\&NotEqual;0\end{array}\right.;$

Eliminate power data (reference data) P of DC component ₀formula is:

P ₀＝F ^-1(S ₀)＝[P ₀[1],...,P ₀[i],....,P ₀[N]] ^T；

In formula, F ^-1(S ₀) be to S ₀carry out discrete Fourier transform; P ₀[i] is the power data (reference data) of elimination DC component, in the data of i-th sampled point.

4. the method determining independent new energy resources system access capacity of energy storing device according to claim 1, is characterized in that: in step 3) in, suppose a characteristic frequency f (T=1/f), then one group of specific power data P ₁formula is:

$S_1\&lsqb;i\&rsqb;=\left\{\begin{array}{cc}0+j0& f_i<0\\ S_0\&lsqb;i\&rsqb;& f_i\&GreaterEqual;0\end{array}\right.;$

P ₁＝F ^-1(S ₁)＝[P ₁[1],...,P ₁[i],....,P ₁[N]] ^T；

In formula, F ^-1(S ₀) be to S ₁carry out discrete Fourier transform; P ₁[i] is specific power data, in the data of i-th sampled point; Specific power data P ₁periodic region between be 0-T.

5. the method determining independent new energy resources system access capacity of energy storing device according to claim 1, is characterized in that: in step 4) in, signal energy is defined as follows:

$E=\sqrt{\underset{i=1}{\overset{N}{\&Sigma;}}x{\&lsqb;i\&rsqb;}^2};$

In formula, E is the energy of signal; X [i] is the power data of i-th sampled point;

ENERGY E ₁with reference energy E ₀the computing formula of ratio is as follows:

η＝E ₁/E ₀。

6. the method determining independent new energy resources system access capacity of energy storing device according to claim 1, it is characterized in that: in step 5) in, the mean value of original power data is set as energy storage power, obtains stored energy capacitance by setup time and energy storage power.